Create a Parallel Compression Bus in Logic Pro 8

When it comes to processing a drum bus, parallel compression is a technique that produces great results on just about any DAW available. Of course, the technique required differs from one application to another. Mo Volans takes the Logical route....

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Step 1  

Start by constructing your drum track using your usual technique. Everyone will have a different method here but for this example I have used purely audio, with a mixture of single hits and loops. It really doesn’t matter if you're using midi, audio or loops as long as each sound can be routed to a bus/group.

It’s a good idea at this point to get a good relative mix and keep things organised by using sensible colours and names for each track. This will avoid things getting messy as you add detail.

Step 2

Next select all your drum tracks and route them to your first available bus. In this case it is bus number one. Select the tracks you want by dragging a box around them in the mixer view or using the shift key to select each one manually. Using this method they will all be routed to the desired bus at the same time. Notice that on doing this Logic Pro will immediately create a new bus/group channel for you. This is due to Logic Pro 8’s useful new workflow feature called dynamic bus allocation.  

Step 3

This newly created bus, named ‘drum master’, will be used to route a reasonably unprocessed version of your drum sound. This bus should ideally retain the original dynamic feel of all your drum parts and not be over-limited or compressed.

With that said, some generic processing can take place here to ensure no rogue transients and frequencies are present. You can see I have applied some light compression and EQ to slightly enhance frequencies already present. Of course, you can use the compressor's mix function if you want a really subtle effect here.  

Step 4

  Once you are happy with this initial bus, select all your drum tracks again in your mixer and navigate to the first send slot of any of these channels. Now select the next available bus. All selected channels will now be sent to this new bus. You can also define the send amount of these channels at this point. A setting of 0db should be perfectly suitable.

Step 5

  This is your parallel compression bus and will be used to add a super-compressed version of your drum track into the mix. It’s a good idea to name and colour the channel at this point to keep things organised.

Step 6

Insert a compressor plug-in on your new bus and dial in some really extreme settings. You can afford to go really over the top here, using settings you wouldn’t normally entertain in normal mixing situations.

Try using Logic’s new vintage modelling feature here, the opto model can do a really good job of emulating that classic 1176 sound.

Step 7

Experiment with the compressor's attack and release settings. When in the opto mode you’ll find that using quite long attack and release times can produce excellent results. Adding some heavy distortion in the extended control area is also a really good method of achieving an overloaded signal.

Don’t worry about using large amounts of gain reduction here. Anything up to and beyond 15db of reduction is perfectly acceptable. Solo the bus to audition it and as long as you're getting a really overloaded, squashed and saturated sound, you're moving in the right direction.

Step 8

Now you can start to strike a balance between the original drum sound and your squashed parallel channel. Try soloing each bus so you can really hear the difference the new compressed signal makes when it's introduced.   Be sure to lean towards the original drum channel as you want to preserve at least some of the dynamic integrity of your overall drum track. The compressed signal should be mixed in to a lesser degree to increase density and volume. 

Step 9

For even more control try routing both these channels to a third bus. This group will act as an overall master and is useful for regaining control over the whole drum level. It also means you won't have to constantly re-balance the uncompressed and compressed signals.  